The present invention is related to a coating composition and coated glass fibers made therefrom containing one or more elastomeric latices to produce coated glass fiber strand having good weaveability for use in woven carpets.
Until recently, jute fibers were used as the fill material for woven carpets, that is, the jute fibers were used as the weft to lock in the pile of the woven carpet. The jute fibers made good carpet fill materials because the fibers were quite strong and reasonably stable. Recently the availability of jute fibers has become a problem. This coupled with the recognition of the lack of uniformity of jute fibers, has led to an effort to replace jute fibers with other materials.
Materials that could be used to replace the jute fibers must be able to withstand the rigors of the weaving process. The weaving process that is performed in producing a woven carpet, involves weaving strands or fibers in along with the carpet pile material so that the carpet pile material constitutes the warp of the woven product while the strand constitutes the weft of the woven product. The weft of the textile fabric is woven generally perpendicularly into parallel strands coming off a beam which is supplied by a source usually mounted on an apparatus which weaves the weft yarn into the warp yarn.
This is in contrast to the production of tufted carpets wherein a woven synthetic carpet backing material is initially provided. Such a carpet backing material is composed of a woven fabric of flat synthetic strands having substantially uniform thickness and width. Suitable synthetic materials are penetrable by a tufting needle that are sufficiently strong to provide an adequate carpet backing. Preferred synthetic materials include polyolefins, and particularly preferred materials consist of polyethylene and polypropylene. These synthetic materials are fashioned into solid ribbons or strands by either direct extrusion into a desired width or thickness or by splitting of sheets of the material at a desired width. Optionally, the strands of the synthetic material may be fashioned to a width wider than the desired width. The wider strand may then be folded to provide either a "U" or a "Z" shaped cross-section. The strands of synthetic material yields a uniform sheet of woven fabric having a thickness equivalent to two strands at every point in the fabric. This form of construction automatically eliminates the irregularities and interstices which are inherent in conventional jute or burlap backing material. The strands are substantially flat and penetrable by a tufting needle, therefore, it is possible for the tufting machine to interlace substantially uniform and parallel rows of tufting yarn by poking the yarn through the woven sheet material. The woven backing material is fed into the tufting machine where the carpet yarn is stitched through the backing to produce loops of carpet yarn on the upper face of the backing.
Glass fibers that constitute continuous glass fibers as well as strands, yarns, cords, and fabrics formed therefrom, have been used to replace jute in the carpet industry, by using the glass fibers in the form of waste tire cord, or glass fiber strand composed of small diameter glass fibers. Glass fibers would make an excellent replacement for jute as fill material in woven carpets because of the uniformity, dimensional and heat stability and strength of the glass fibers. Such a replacement of jute by glass fiber strand would require the glass fiber strand to have good weaveability.
Weaveability is a characteristic that glass fiber strand must have to undergo satisfactorily the weaving process in producing woven carpet. The glass fiber strand would be wound around a cop inside a shuttle of a weaving loom. The shuttle is transported, or in the case of a shuttless loom the strand itself is transported back and forth across the loom so the strand unravels from the cop to supply the weft in between the warp strands of pile material running perpendicular to the weft strands. As the strands unravel, it is coiled to some degree due to its previously wound condition. The coiled strand is vulnerable to breakage from the force applied to it in being transported across the loom. To avoid breakage from this force, the strand should have a good knot tensile strength. The knot tensile strength as measured by the American Society of Testing Materials (ASTM) standard D-2256 measures the tensile strength of the strand when folded over itself in a knot. Generally, glass fiber strand composed of glass fibers having small diameters have better weaveability than strands composed of coarser glass fibers. The problem with this is that the strands composed of fine glass fibers are more expensive to produce.
In the past when using glass fibers in producing carpet backing for tufted carpets the glass fibers have been coated with materials such as vinyl plastisols and acrylic-acetate (U.S. Pat. No. 3,642,516, Gasaway et al). Also, carpet backing materials have had applied to them adhesives such as an aqueous dispersion of carboxylated styrene-butadiene latex compound modified with melamine formaldehyde resin additive (U.S. Pat. No. 3,864,195 and U.S. Pat. No. 3,741,854).
It has recently been suggested to use coarser glass fibers with a coating composition having an elastomeric latex and an external plasticizer to produce coated glass fiber strands with improved weaveability. The elastomeric latex is a butadiene styrene latex and carboxylated derivatives thereof and the external plasticizer is soluble or dispersible or emulsifiable into the latex but not incorporatable into the polymer backbone of the elastomer. Such an external plasticizer is a petroleum hydrocarbon processing oil.
It has recently been discovered that the use of a coating composition containing a petroleum hydrocarbon processing oil with glass fibers leads to several processing problems. These problems include difficulty in emulsifying the oil, production of smoke under conditions of elevated temperature, and build-up of coating material on pulleys and traversing equipment.
It is an object of the present invention to provide a coating composition and coated glass fiber strands having good weaveability and also having improved processibility.